Bleeding automotive brake systems of air and other contaminants is an important process in vehicle maintenance.
Air can enter a brake system in many ways, such as: (1) when a leak occurs and allows air to be vacuumed into the system through the point of leakage; (2) when the fluid level of the reservoir decreases to a point that allows air to be directly injected into the system; (3) when parts are replaced or repairs are made to a hydraulic brake system; or (4) when improper brake bleeding techniques are utilized.
When air is present in a brake system the air compresses when pressure is applied. This lowers the hydraulic pressure available to the caliper pistons, thus lowering the overall braking power. The brake pedal seems "mushy" or "spongy" to the user.
It is not uncommon for individuals to tolerate "spongy brakes" because the bleeding of a brake line is a somewhat detailed, painstaking process.
The brake bleeding process most commonly requires the cooperation of two people. This can be costly to a business in terms of man hours spent per patron; and the two person requirement may be awkward to a home mechanic who customarily works alone.
One person must sit inside the vehicle and operate the brake pedal, and a second person is needed to operate the valve fitting located on the brake caliper units, one wheel at a time. The two individuals must cooperate and work in unison with one another. A brief order of activities would be: Open the valve; pump the brake pedal; close the valve and release the pedal; then repeat the process until all air and contaminants are removed from the brake system. In the prior art brake bleeding systems, one person working alone could not achieve this.
Prior art patents which deal with these problems are U.S. Pat. Nos. 4,170,280, 4,201,056, 3,183,673, 2,670,874 and 2,872,951. Many others were found fitting the descriptions of "permanently mounted", "temporarily mounted" and "Duck Bill" check valves.
Prior art brake bleeders require a source of air pressure to pressurize the brake fluid holding container, whereas the device of this invention operates on a vacuum created by the motion (push and then release) of the brake pedal.
Brake bleeding in all of the above-mentioned patents requires inspecting the fluid immediately past the fluid check valve, since view of the fluid is prevented between the check valve and bleeder in those other systems. Meanwhile, entry of air into the brake system due to a defective check valve or other defects, cannot be monitored because tubing inspection is inhibited by the check valve itself. Thus, a need exists for a brake bleeder device adapted for operation by one person or operator which allows for direct inspection of the fluid as it exits the brake system bleeder valve.